What qualifies actors for a slot on Yahoo Movies' running list of the 50 Greatest Actors Alive? First, we limited the pool to actors who are still currently working. Other factors taken into consideration: Pure skill in the craft; their ability to disappear underneath the skin of the characters they portray; versatility and the range of their roles; ratio of strong performances to weak ones; quality of films acted in; strength of recent work; awards and accolades from peers.